AITA for cancelling our wedding after finding out my fiancé has a daughter?

I (25F) and my fiance (28M) have been dating for 6 years. I am so happy with him, he's a good man and I love him and wanted to spend my life with him. Back in August we started thinking about having kids and looking at houses. We found our dream house and were looking at schools in our area.<br><br>From out of the blue, he confessed to me that he'd been cheating on me with this girl 8 years her junior. He said that he realized he was in love with her, and that it was an affair that started 2 years into our relationship.<br><br>He told me they have a daughter (5) and that the mother was pregnant with our wedding in full swing. He offered to pay for everything and even offered to cancel the wedding and give me a full refund, but that it's her daughter and he wants the little girl in his life.<br><br>I was devastated. I was angry that he hid this from me, I was heartbroken over this, and I was reeling over the fact that he's been with someone else and had a child with her when we were together. I told him I need time to process this, and that his answer was the ultimate AH moment - he's choosing the woman he was cheating with and her daughter over me.<br><br>He's now tried to apologize and make amends, but he's also told me he won't be giving up his daughter's birthday or wedding, and that if I can't support him through this, then I'm not the right woman for him. I told him to fuck off, but I don't think I can go through with this wedding. I know it sucks, but I just don't see how I can after finding this out. AITA?